The invention relates to an articulated support for manually-operated power tools, and a method for controlling the operation of such tools operation so as to enable one or more selected tool functions based upon a determined tool position.
The prior art has recognized the desirability of making the operability of a manually-operated or xe2x80x9chand-heldxe2x80x9d power tool conditioned on the proper placement of the tool relative to a work. Thus, the prior art is replete with the use of normally-open contact-based xe2x80x9climitxe2x80x9d or xe2x80x9cproximityxe2x80x9d switches on the tool that ensure that a given tool operation can be performed only when the working end of the tool is placed in direct physical contact with the face of the work. Other known systems include the use of noncontact proximity sensors, situated either on the tool itself or on an adjacent fixture, to similarly determine whether the tool has been properly positioned relative to the work prior to enabling a select tool function. Such switches or systems often enable/disable a selected tool function either directly, as through use of a mechanical interlock, or indirectly, as by interrupting the communication, for example, of either power or an enabling control signal to the tool.
Unfortunately, such prior art switches or systems may fail to detect a false enable signal, as when the working end of the tool is placed in contact with a wrong location on the work in such a way as to otherwise generate the requisite enable signal. As yet another example of a circumstance in which a false enable signal is generated, where the tool includes a rotary spindle supporting a socket for tightening a threaded fastener, a false enable signal is readily achieved when the socket is only partially seated on the head of the intended fastener, whereupon the tightening operation likely will fail to achieve a desired torque.
A further instance where difficulties arise in the prior art is when multiple operations are to be performed by the tool on a given work. For example, it may be desirable to tighten or xe2x80x9ctorquexe2x80x9d a plurality of threaded fasteners on a given assembly at a single workstation, perhaps in a predetermined sequence. In order to ensure that each fastener is properly tightened by a manually-operated tool, the prior art has resorted to multiple-spindle tools that are capable of simultaneously driving all of the fasteners with a single tool placement, thereby reducing the likelihood that a desired torque has not been successfully applied to a given fastener by the tool operator. Unfortunately, such multiple spindle tools are significantly more expensive than single-spindle tools and, further, must be dimensionally adapted for each specific application in order to simultaneously torque each of the multiple fasteners, thereby further increasing tool costs and reducing assembly design flexibility. Such tools are also typically larger, heavier and, perhaps, less maneuverable than single-spindle counterparts.
Accordingly, what is needed is a system and method for use with a manually-operated power tool that enables a select tool function based upon a detected position of the tool relative to the work.
It is an object of the invention to provide an articulated support for a manually-operated power tool with which to enable at least one select tool function based upon the relative position of the articulated support""s elongate segments.
It is also an object of the invention to provide an articulated support for a manually-operated power tool that is useful in monitoring whether each of a series of selected tool operations are successfully performed by a tool operator, and the sequence of such tool operations.
It is a further object of the invention to provide an articulated support for a manually-positioned power tool that conditions a select tool operation upon a proper positioning of the tool, by a tool operator, relative either to a fixed base or a given work.
Yet another object of the invention is to provide a method for operating a manually-operated power tool based upon a determined tool position.
In accordance with the invention, an articulated support is provided for a manually-operated power tool whose operation is characterized, when mounted on the articulated support, by movement of the tool to at least one predetermined tool position in which a selected tool operation is to be performed on a work. Under the invention, the articulated support includes a pair of rigid elongated segments connected end-to-end to form a joint permitting rotation of one segment relative to the other segment about a joint axis, whereby a joint angle is formed at the joint; and a first sensor generating a first output signal representative of a joint angle formed between the connected segments about the joint axis. The articulated support further includes a controller for the power tool receiving the first output signal, wherein the controller determines an indicated position for the tool based at least in part on the first output signal and enable the first operation of the tool when the indicated position is the predetermined tool position. An exemplary embodiment of the articulated support further includes a second sensor generating a second output signal representative of a base angle formed between the one segment and the base about the base axis, with the controller further determining the indicated position based on the second output signal. A proximity sensor can further be used to generate a third output signal representative of a distance achieved between one segment and one of the base and the work, with the controller further determining the indicated position based on the third output signal.
In accordance with an aspect of the invention, if the tool includes a trigger switch generating a trigger signal for triggering the selected operation, the controller preferably enables the selected operation in response to the trigger signal only when the indicated position is the predetermined position.
In accordance with another aspect of the invention, a method is provided for controlling a selected operation of a manually-operated tool that is supported relative to a fixed base by an articulated support mounted on the base, wherein the articulated support includes an arm formed by at least two rigid elongated segments connected end-to-end, and each adjacent pair of connected segments define a respective joint permitting rotation of one segment of each pair relative to the other segment of each pair about a respective joint axis. The method includes determining an indicated position for the tool relative to the base based at least in part on a relative joint angle formed between a pair of adjacent segments; and enabling the first tool operation when the indicated position of the tool is a predetermined position relative to the fixed base in which the first tool operation is to be performed. Under the method, determining the indicated position is preferably based upon the output signals generated by one or more angle sensors that are responsive to instantaneous angles formed between the base and the arm""s first segment, or between an adjacent pair of connected segments.
In accordance with yet another aspect of the invention, the method may further preferably include determining whether the tool is within a predetermined proximity of a work, and enabling the first tool operation only when the indicated position of the tool is the predetermined position and the tool is within the predetermined proximity of the work. By way of example only, determining whether the tool is within the predetermined proximity of the work may include detecting a distance between a reference surface on the work and one of the tool and the support.
Also under the invention, a method for operating a power tool preferably includes determining an amount of time that the tool is substantially maintained in the predetermined position. The method further preferably includes comparing the determined amount of time that the tool is substantially maintained in the predetermined position with a predetermined minimum time period for completing the selected tool operation.